The mystery surrounding how the Pearson patriarch died has been an ongoing question since early in the season, but on Tuesday’s episode, titled “What Now?,” the picture may have gotten a whole lot clearer. Following William’s “fun-eral” (Randall’s words, not ours) and Kevin’s successful play opening, Kate finally dropped a huge bombshell about her dad’s death: She is the reason he died.

See, back in the ‘90s, when Kate, Kevin and Randall were teenagers, the cracks in Jack and Rebecca’s marriage were starting to become chasms -- and Kate was the only one to notice. Red flags started to go off in 15-year-old Kate’s head when she saw Jack barely give Rebecca a kiss goodbye on the cheek as she left for her two-week, five-city tour with her band (the one with her old flame, Ben).

After Jack dropped The Big Three off at a friend’s house for a party, Kate stayed back, pushing her dad to make the two-hour drive to Cleveland, Ohio, where Rebecca’s first show was, instead of spending it alone at the house. “Are you and mom alright? You don’t seem fine,” a worried Kate said, prompting Jack to try and reassure her -- and not doing a very good job of it: “It’s marriage. It’s … stuff. We’re fine.”

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When Kate asked why he wasn’t making the effort, Jack pulled the parent card and suggested she focus on her life and not her parents’ marital issues. “You’ve got more important things to worry about, being a teenager: boys and grades and a band that sounds like they’re always kidding -- what’s their name, Weezer? Your mom and dad, we’re the last thing in the world you need to worry about, OK?”

Taking Kate’s advice, Jack reluctantly went to the bar where his co-worker was having his retirement after-party (and where Miguel’s assistant, Heather -- the one from an earlier episode -- unsuccessfully hit on Jack) for a few beers. It was after Jack had one too many drinks that he decided that Kate was right: He had to make a grand gesture to try and rectify his marriage.

“Hey princess, it’s dad,” a slightly buzzed Jack said to Kate over the phone outside the bar in what may have been their last conversation ever. “I wanted you to know that you were right. I’m going to fix things with your mom. I love you Katie girl.” Signs of trouble (and dread) became apparent when Jack stumbled to grab the car keys he dropped on the ground after he hung up the phone, later stepping behind the wheel to, presumably, make the two-hour trek to Cleveland to see his wife.

And of course, this crazy dark open ending left us begging for more answers. Did Jack get into a drunk-driving accident on his way to Cleveland and fail to make it? Or does he make it safely make it to Cleveland, but couldn’t fix his marriage to Rebecca, leading him to go down an alcohol-fueled downward spiral? Did we just see his final moment with the Big Three?!

In the present day, William’s memorial service -- thrown by Randall and Beth’s young daughters at William’s insistence -- dredged up a mixture of emotions for Kate in regards to Jack’s death: guilt, sadness and regret likely among them. “You remember when I told you I couldn’t talk about my dad’s death?” Kate told Toby later, who had been dying (no pun intended) for a real conversation about Jack for a while now. “That’s because it’s my fault. I’m the reason that he’s dead.”

Kate’s confession explained a lot about why she had the most emotional reactions out of the Pearson family whenever Jack’s death came up, and also provided context as to why she was the one who had his urn. Knowing that Jack died when Kate, Kevin and Randall were teenagers -- likely around the time of this episode’s flashbacks -- it seems as though his days (maybe even hours) are numbered.

It should be noted that it was this line from Beth’s impromptu remembrance of William that led to a heartbreaking breakdown by Kate at one point in the episode: “We’ll remember things as before William and after William,” neatly paralleling the family’s past grief with Jack. To calm Kate down, Randall shared a dream he had where his two late fathers met, trading stories about Randall like old friends.

Randall also had a lot going on in his own life, patching things up with his mother, Rebecca, and quitting his job. As for Kevin, he's about to be torn between his career and his heart once again, after getting an offer from Ron Howard to film a movie in L.A. after telling ex-wife Sophie he went back to New York City for her.

ET was recently with Milo Ventimiglia, who plays Jack, where he rightly warned that the final episodes -- including Tuesday’s -- were “stressful.”

“Even though things may be crumbling or in disrepair or up in the air, the skies will part, the clouds and the sun will shine again,” Ventimiglia said, coyly teasing that answers to Jack’s death could come sooner than expected. “It could be the next episode. It could be the second to last episode. It could be a ways away.”

Creator Dan Fogelmanrecently explained his mindset behind doling out morsels of information in regards to Jack. “The needle we have to continue to thread is sparsing out information,” he said. “There’s a hinge in this family, and it’s the before with Jack and the after. That’ll be interesting in future seasons as we go forward to show where that hinge was, what happened to the family before and after.”

“You’ll learn when … and then, much later, how,” he promised, speaking more directly to Jack’s death, adding that “hopefully that’ll take many, many episodes.” Could we be getting that answer in the finale? No matter when it’s revealed, we’re betting it’s going to be devastating.